1. Make caramel by slowly dissolving the sugar with 2 tablespoons water in a saucepan over a low heat. Bring to a slow simmer without stirring. When syrup starts to colour around the edges, swirl saucepan gently to allow caramel to cook uniformly. Do not stir but allow it to become dark brown. Take off heat and mix in butter.

2. Pour over boiling hot cream and continue mixing until smooth. If there are any lumps of hardened caramel let them dissolve in the warm cream before adding the other ingredients.

3. Add the chocolate and wait for a minute or two for it to melt, then mix gently. Stir in egg yolks. Whisk egg whites until firm but not soft peaks and fold into mixture.

4. Divide between 6 ramekins. Chill for 6 hours.

William Ledeuil's white chocolate soup

Break the chocolate into 2cm pieces and place in a bowl large enough to contain the liquid. Mix the coconut milk and passion fruit nectar in a small saucepan, and heat. (If you are using lemongrass, allow it to steep some in the hot coconut milk mixture.) Pour the hot liquid over the white chocolate pieces and allow to sit for 3-4 minutes before stirring.

Melt the butter and the chocolate together in the microwave or over a bain marie. Let it cool slightly before adding the eggs, then the sugar and the sieved cocoa powder.

In a 2 litre or so terrine mould (silicone is good) pour in a layer of this mixture to line the bottom to about 1.5 cm. Place a layer of bars and a few Maltesers, so as they run the whole way through the length of the terrine. Press them lightly into the chocolate base.

Repeat until you've used up the ingredients and the terrine is tightly packed.

Put the cake in the fridge, let it chill and harden for about 3 hours. Slice carefully, exposing the extraordinary, fossil-like cross-section of the bars.